Labour leader Ed Miliband today pledged that the party will increase the minimum wage if it wins the general election.

He told the national conference of the GMB union that Labour would not just increase the statutory rate, it will narrow the gap between the minimum wage and average earnings.

"A country can only succeed if those who work hard and do the right thing get a fair day's pay. That's why I guarantee today: the next Labour government will increase the minimum wage."

He told delegates at the Nottingham conference that a Labour government would also act on loopholes in rules on agency workers which he said were used to undermine the pay of permanent employees.

Aides said Mr Miliband's pledge on the minimum wage was more "vivid" than previously stated.

The Labour leader added that quality jobs were being hit by zero hours contracts "spreading like wildfire", saying: "There's no place for exploitative zero hours contracts in Britain today. So the next Labour government will have a simple rule - if week after week you do regular hours, you deserve a regular contract, not a zero hours contract."

Mr Miliband also pledged that a Labour government would help more employers to pay the living wage, which is currently set at £7.65 an hour and £8.80 in London, well above the minimum wage, which will rise to £6.50 in October.

He said there was a "low pay epidemic" in Britain which had been coming for generations and "shames us all", stressing that a living wage would benefit business by improving productivity and reducing staff turnover.

Employers would be stopped from putting 15 people in a house to "sidestep" the minimum wage.

Mr Miliband laid out Labour's plans to build more houses, freeze energy prices and "save" the NHS, which he said was "going backwards" under the Tories.

"It will be up to the next Labour government to protect and improve our NHS, stop the Tory privatisation and repeal the Health and Social Care Bill."

There were no new policy announcements in the speech to the GMB, which has cut its funding to Labour by £1 million a year amid controversy over reforms to the historic link between the party and trade unions.

In a question and answer session with delegates, Mr Miliband was pressed on what Labour will do to stop abuses of zero hours contracts, boost wages, deal with immigration and tackle the privatisation of education services.

Liverpool delegate Ian Lowes asked if the Labour leadership will support local government workers who are balloting for strikes over pay.

He asked if Labour would back the workers or repeat the "disgraceful" comments during the long-running dispute over public sector pensions.

"Labour needs to decide whose side it is on - the workers or the bosses."

Mr Miliband replied that some of the "bosses" were Labour mayors having to deal with spending cuts imposed by the Government, such as in his Doncaster constituency which is having to save £109 million.

He said: "The answer has got to be to carry on discussions between the Local Government Association, councils and the workforce."

He assured the union that Labour was determined to change the "business model" of zero hours contracts, as well as aiming to close the gap between the minimum wage and average earnings.

"The lunacy of low pay is that the Government is doling out subsidies to employers. It will be an absolute core of my government to tackle the scourge of low pay."

Mr Miliband praised the GMB for speaking out against Scottish independence and criticised attacks against author JK Rowling after she donated £1 million to the No campaign.

"We have seen over the last 24 hours the most unpleasant and unseemly attacks on JK Rowling. All leaders should say this has no place in the debate about independence."

Mr Miliband was warmly received by the delegates, who he thanked for their "warm welcome."

He predicted that next year's general election would be the closest in a generation, saying Labour would have a "massive fight" in the coming months.

Labour had its differences with unions, but Mr Miliband added: "There is a common cause and a common agenda about the workplace, low pay, housing, inequality and the cost of living crisis."

Mr Miliband suffered a wardrobe malfunction on his way to Nottingham when he spilled coffee on his shirt.

Aides dashed out to buy a new one and arranged to have an iron and ironing board sent to a room in the conference centre where Mr Miliband was preparing for his speech, to iron out creases.